.fade-enter-active, .fade-leave-active {
    transition: all .5s;
    transform:  translateY(0px) ;
    opacity: 1;
}
.fade-enter, .fade-leave-to /* .fade-leave-active below version 2.1.8 */ {
    opacity: 0;
    transform:  translateY(100px) ;
}

.drop-menu-color {
    background-color: white;
}

.drop-menu-search {
    text-align: left;
}

.el-drawer__body {
    overflow-y: auto;
}

.topnav {
    height: 40px;
    line-height: 40px;
    display: flex;
    flex-flow: row nowrap;
    justify-content: space-around;
    color: #4c4040;
}
.nav-icon {
    padding:0;
    margin:0;
    font-size:1.5em;
    font-family: Arial;
    font-weight: bold;
    font-style: italic;
}

.nav-icon > p{
    padding:0;
    margin:0;
}

.nav-container {

}

.search-container {
    flex-grow: 0;
}



.nav-container > ul {
    padding: 0;
    margin: 0;
    list-style: none;
}

.nav-container > ul > li {
    display: inline;
    cursor: pointer;
}

.nav-container > ul > li {
    float:left;
    position:relative;
    padding:12px 20px;
    color:#000;
    line-height:1;
    transition:0.2s all linear;
    list-style:none;
    cursor:pointer;
}
.nav-container > ul > li::before {
    content:"";
    position:absolute;
    top:0;
    left:100%;
    width:0;
    height:100%;
    border-bottom:3px solid #000;
    transition:0.2s all linear;
}
.nav-container > ul > li:hover::before {
    width:100%;
    top:0;
    left:0;
    transition-delay:0.1s;
    /*过渡延迟*/
    border-bottom-color:#000;
}
.nav-container > ul > li:hover ~ li::before {
    left:0;
}
.nav-container > ul > li:active {
    background:#000;
    color:#fff;
}

.topnav a.active {
    background-color: #2196F3;
    color: white;
}

.topnav input[type=text] {
    padding: 5px;
    margin: 4px 10px;
    font-size: 17px;
    border: none;
}

.topnav .search-container button:hover {
    background: #ccc;
}